C#•5mo ago

✅ WPF Image tooltip display issue in fluent style with .NET 9

I upgraded a wpf project to .net 9 recently to try out the new fluent style. I set the

ThemeMode="Dark"

ThemeMode="Dark"

ThemeMode="Dark"

ThemeMode="Dark" property in app.xaml.

I have a simple image that I display in a smaller size, and there's a tooltip inside that displays the image in its original size. This is the markup I have for it:

<Image HorizontalAlignment="Left"
       Stretch="Uniform"
       Source="{Binding Path=CoverImage, 
            Converter={StaticResource ByteArrayToBitmapImageConverter}}" 
       Grid.Row="1"
       Height="300">
    <Image.ToolTip>
        <Image RenderOptions.BitmapScalingMode="Fant"
               Stretch="Uniform"
               Source="{Binding Path=CoverImage, Converter={StaticResource ByteArrayToBitmapImageConverter}}" />
    </Image.ToolTip>
</Image>

<Image HorizontalAlignment="Left"
       Stretch="Uniform"
       Source="{Binding Path=CoverImage, 
            Converter={StaticResource ByteArrayToBitmapImageConverter}}" 
       Grid.Row="1"
       Height="300">
    <Image.ToolTip>
        <Image RenderOptions.BitmapScalingMode="Fant"
               Stretch="Uniform"
               Source="{Binding Path=CoverImage, Converter={StaticResource ByteArrayToBitmapImageConverter}}" />
    </Image.ToolTip>
</Image>

<Image HorizontalAlignment="Left"
       Stretch="Uniform"
       Source="{Binding Path=CoverImage, 
            Converter={StaticResource ByteArrayToBitmapImageConverter}}" 
       Grid.Row="1"
       Height="300">
    <Image.ToolTip>
        <Image RenderOptions.BitmapScalingMode="Fant"
               Stretch="Uniform"
               Source="{Binding Path=CoverImage, Converter={StaticResource ByteArrayToBitmapImageConverter}}" />
    </Image.ToolTip>
</Image>

<Image HorizontalAlignment="Left"
       Stretch="Uniform"
       Source="{Binding Path=CoverImage, 
            Converter={StaticResource ByteArrayToBitmapImageConverter}}" 
       Grid.Row="1"
       Height="300">
    <Image.ToolTip>
        <Image RenderOptions.BitmapScalingMode="Fant"
               Stretch="Uniform"
               Source="{Binding Path=CoverImage, Converter={StaticResource ByteArrayToBitmapImageConverter}}" />
    </Image.ToolTip>
</Image>

If I set

ThemeMode="None"

ThemeMode="None"

ThemeMode="None"

ThemeMode="None" in app.xaml to get the previous default styling behavior, I get the regular behavior where the tooltip displays the image's full size.

But with the new fluent style, it seems that the tooltip (or image?), the tooltip is scaled down significantly.

I attached two images below to show the difference. First image has the behavior I want with the tooltip.
The 2nd image has the fluent dark style specified in the app.xaml and it changes how the tooltip is displayed. The same image is used with both screenshots.

Is there a way I can view the specified styles by the new fluent styling? I'd like to override whatever styling is applied to the tooltip/image :ThonkAnime: Or maybe there's a different way I could specify this markup?

HFrederickOP•8/19/25, 8:51 AM

Here are the images:

HFrederickOP•8/19/25, 8:57 AM

Just in case, this project doesn't use any external styling library or use a resourcelibrary. So it's just default wpf styling and I just specify

ThemeMode="Dark"

ThemeMode="Dark"

in app.xaml.

For the image I'm passing to the "CoverImage" field, it's a 1400x1982 jpg file as a byte array if it matters. I use a converter to change it from a bytearray into a bitmap image

HFrederickOP•8/19/25, 2:45 PM

Mark this as solved :kannakms:

Somewhere in the fluent dictionary styles, there's some definition for a MaxWidth="400"MaxWidth="400" property for every ToolTip control :kleeMAD:

If I specify a different maxwidth and width directly on the tooltip instance, I can display my tooltip like it does on default wpf styling

✅ WPF Image tooltip display issue in fluent style with .NET 9

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